Waste receptacle

ABSTRACT

A waste cart includes a base housing; a center upright having a proximal end and a distal end, wherein the proximal end is secured to the base housing; a top housing secured to the distal end of the center upright, wherein the top housing has two or more disposal openings for two or more separate disposal portions including, a first waste portion which has a first metal detector and an indicator for providing a notification when a metal item passes through the opening; and a second waste portion which includes a second metal detector and an indicator for providing a notification when a metal item passes through the opening; an electronics module which operates each metal detector independently; and an alarm indicator operationally associated with the electronics module which is activated when the electronics module detects the passage of a metal item through an opening into a waste portion.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation-in-part of, and claims thebenefit under 35 U.S.C. 120 to, U.S. patent application Ser. No.14/815,605, filed Jul. 31, 2015, the disclosure of which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a waste cart capable of detectingmetallic objects as they pass through the cart's openings as disclosedherein below. The medical environment tends to generate three main formsof trash: sharps, biohazard materials, and ordinary trash. Hospitalstaff tends to waste money by negligently discarding equipment aftersurgery, typically by unintentionally depositing metal items (e.g.,surgical tools) into the trash along with disposable garments (surgical“scrubs”) and other potentially hazardous biological waste. Theincorporation of a metal detector with a trash can helps to alleviatethis problem.

Medical environments outside the hospital (e.g., doctors' offices,hospital rooms, and surgical suites) must also put proper protocols intoplace for the safe disposal of “sharps”. Federal regulations (e.g., 49CFR 173.134) define a “sharp” as any object that may be contaminatedwith a pathogen and that is capable of cutting or penetrating skin or apackaging material (and thus leading to injury or disease transmissionor both). Sharps include items such as needles, scalpels, broken glass,culture dishes, etc. Federal regulations (e.g., 49 CFR 173.197) requirethat sharps be placed in containers that are rigid, leak resistant,impervious to moisture, strong enough to prevent tearing or burstingduring normal conditions of transport, and puncture resistant.

U.S. hospitals produce an estimated 6,600 tons of waste daily and4,000,000,000 pounds annually. Within the hospital, operating rooms tendto generate two main forms of trash: single use sterilized equipment andregular garbage which is sometimes needlessly bagged as hazardous waste.The well-recognized red bags are intended to be used for medical wastethat requires more cautious—and thus more expensive—disposal procedures.Some research indicates, however, that up to 90% of items disposed inspecial red bags are simply regular trash that could be stored in aclear bag and disposed of more conveniently. Thus, a more efficientsegregation and disposal of trash could provide significant cost savingsin the healthcare industry.

Medical disposal and detector systems currently available have a numberof shortcomings. In some, the openings are unfinished and expose thecontents of a biohazard bag. The structural materials wear and lack therigidity of conventional industrial disposals. Because a sterileenvironment is a fundamental hospital goal, certain types ofplastics—especially inexpensive ones—do not necessarily reassure theuser as to their cleanliness. Some plastics interact slightly withhospital cleaning materials and develop an undesired sticky texture. Insome cases the structures are angular with protruding surfaces andcorners, which in turn can catch on medical clothing and draping.

Many structures are singular in their function, so that separate itemsare needed for the several types of expected waste, which in turn tendsto crowd the medical space in an undesired, or in some cases an unsafeor unsanitary, manner.

Appropriate devices must also meet medical regulations for safelystoring biohazard materials. The Bloodborne Pathogens Standard of theU.S. Occupational Safety and Health Administration (OSHA) uses the term“regulated waste” to refer to waste items such as:

-   -   liquid or semi-liquid blood or other potentially infectious        materials (OPIM);    -   items contaminated with blood or OPIM and which would release        these substances in a liquid or semi-liquid state if compressed;    -   items that are caked with dried blood or OPIM and are capable of        releasing these materials during handling;    -   contaminated sharps; and    -   pathological and microbiological wastes containing blood or        OPIM.        With these standards in place, disposal devices generally accept        the standard “red bag” used in the hospital environment. The        device must be waterproof so that it can be cleaned easily and        completely and those portions of devices that are in contact        with hazardous materials must be formed of a material that is        impermeable rather than porous.

Changing a bag in conventional devices can be both time consuming andinefficient due to their structure and configuration. Systems thatrequire significant user strength are unacceptable in the hospitalenvironment because much work is done by smaller persons. For example,on a percentile basis, in order to capture 99% of potential users, thedevice should be easily handled by a middle-age female. Additionally,existing devices may preclude access to the full bag or to new bags, aresometimes improperly balanced, may not withstand the weight strain of anoverly full or leaning load, and do not offer any method of separatinglarge and small biohazard materials, or provide a separate area fordisposing of non-biohazard materials.

Additionally, loss of expensive metallic items such as tools, templates,and other devices plague industries which are unrelated to medicine suchas machine shops, automobile garages, assembly plants, laboratories,manufacturing plants, and similar facilities. These industries willbenefit equally from a newly improved waste cart.

Hence, a need exists for a waste cart capable of detecting metallicobjects as they pass through the cart's openings.

SUMMARY OF THE INVENTION

A waste cart comprises: a base housing; a center upright having aproximal end and a distal end wherein the proximal end is secured to thebase housing; a top housing secured to the distal end of the centerupright, the top housing having two or more disposal openings for two ormore separate disposal portions; a first waste portion which has a firstmetal detector and an indicator system for providing a notification whena metal item passes through the opening; a second waste portion whichincludes a second metal detector and an indicator system for providing anotification when a metal item passes through the opening; anelectronics module which operates each metal detector independently orin conjunction with each other; and an alarm indicator operationallyassociated with the electronics module which is activated whenever theelectronics module detects the passage of a piece of metal into a wasteportion.

DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, there is shown in thedrawings a form that is presently preferred; it being understood,however, that this invention is not limited to the precise arrangementsand instrumentalities shown.

FIG. 1 is a front view of one embodiment of the present invention.

FIG. 2 is a top-down view of one embodiment of the present invention.

FIG. 3 is a perspective view of one embodiment of the present invention.

FIG. 4 is a side view of one embodiment of the present invention.

FIG. 5 is a bottom-up perspective view of one embodiment of the presentinvention.

FIG. 6 is a bottom-up view of one embodiment of the present invention.

FIG. 7 is an exploded side view of one embodiment of the presentinvention.

FIG. 8 is an exploded view of the top components of one embodiment ofthe present invention.

FIG. 9 is an exploded view of the tower components of one embodiment ofthe present invention.

FIG. 10 is a bottom-up perspective view of the base of one embodiment ofthe present invention.

FIG. 11 is a diagram of a detection algorithm of one embodiment of thepresent invention.

FIG. 11A is a diagram illustrating the acquisition of ananalog-to-digital converter (ADC) value of one embodiment of the presentinvention.

FIG. 12 is a diagram illustrating an ADC reading showing acharacteristic curve of one embodiment of the present invention.

FIG. 13 is a diagram illustrating an ADC reading showing positive andnegative deflections of one embodiment of the present invention.

FIG. 14 is a diagram illustrating an ADC reading showing acharacteristic curve and sampling points of one embodiment of thepresent invention.

FIG. 15 is a diagram illustrating an ADC reading showing acharacteristic curve and a detection threshold window of one embodimentof the present invention.

FIG. 16 is a diagram illustrating an ADC reading showing acharacteristic curve and illustrating one embodiment of a positivedeflection in the present invention.

FIG. 17 is a diagram illustrating an ADC reading showing acharacteristic curve and illustrating one embodiment of a negativedeflection in the present invention.

FIG. 18 is a diagram illustrating an ADC reading showing acharacteristic curve and illustrating one embodiment of backgroundcompensation in the present invention.

FIG. 19 is a diagram illustrating an ADC reading showing acharacteristic curve and illustrating one embodiment of signal clippingin the present invention.

FIG. 20 is an exploded perspective view of a coil subassembly includingframework for holding the coils of one embodiment of the presentinvention.

FIG. 21 is a perspective view of one embodiment of the presentinvention.

FIG. 22 is a perspective view of one embodiment of the presentinvention.

FIG. 23 is an illustration of a perpendicular coil arrangement and theassociated detection fields of one embodiment of the present invention.

FIG. 24 is a perspective view of a perpendicular coil arrangement of oneembodiment of the present invention.

FIG. 25 is a mid-level diagram of one embodiment of the presentinvention.

FIG. 26 is a diagram of the master/slave synchronization setup of oneembodiment of the present invention.

FIG. 27 is a diagram of the installed wiring synchronization setup ofone embodiment of the present invention.

FIG. 28 is a side view of an RFID detector used in one embodiment of thepresent invention.

FIGS. 29-37 schematically illustrate steps and routines performed byprocessor-executable code for performing one or more methods ofdetection in waste receptacles in accordance with preferred embodimentsof the present invention.

DESCRIPTION OF THE INVENTION

The present invention now will be described more fully hereinafter inthe following detailed description of the invention, in which some, butnot all embodiments of the invention are described. Indeed, thisinvention may be embodied in many different forms and should not beconstrued as limited to the embodiments set forth herein; rather, theseembodiments are provided so that this disclosure will satisfy applicablelegal requirements.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed items. As used herein, the singularforms “a,” “an,” and “the” are intended to include the plural forms aswell as the singular forms, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, steps, operations, elements, components, and/or groupsthereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by onehaving ordinary skill in the art to which this invention belongs. Itwill be further understood that terms, such as those defined in commonlyused dictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and thepresent disclosure and will not be interpreted in an idealized or overlyformal sense unless expressly so defined herein.

In describing the invention, it will be understood that a number oftechniques and steps are disclosed. Each of these has individual benefitand each can also be used in conjunction with one or more, or in somecases all, of the other disclosed techniques. Accordingly, for the sakeof clarity, this description will refrain from repeating every possiblecombination of the individual steps in an unnecessary fashion.Nevertheless, the specification and claims should be read with theunderstanding that such combinations are entirely within the scope ofthe invention and the claims.

Looking at FIGS. 1 through 10 and 20-22, there is illustrated oneembodiment of a movable waste cart 10 which is capable of detectingmetallic objects as they pass through the cart's openings 56,57. Thewaste cart 10 is comprised of a mostly non-metallic composition. Thewaste cart 10 is comprised of three primary sections which include: (1)a base housing 20 which is proximally closer to the ground, (2) a centerupright body 40 which is the region disposed between the top housing 50and base housing 20, and (3) a top housing 50 which is the regionfurthest vertically from the base housing 20.

The base housing 20 includes an upper surface 22 and a lower surface 24.The center upright body 40 is secured to and emanates upward from theupper surface of the base housing 20. A battery cover 25 is located onthe lower surface of the base housing. In one embodiment of the presentinvention, the base housing 20 is essentially hollow and includes aninner cavity 30 which houses some or all of the electronic componentsutilized by the waste cart 10. In another embodiment, the inner cavity30 houses the electronics module 90, battery 89 (FIG. 25), and otherelectrical components.

The center upright body 40 has a proximal end 42 and a distal end 44where the proximal end is secured to the base housing 20 and the distalend is secured to the top housing 50.

The top housing 50 is mainly circular in nature and is bisected, withtwo or more cart openings for two or more separate disposal portions.The openings may be symmetrical. In a variation of the cart 10 as shownin FIGS. 2 and 3, a divider 59 extends within and bisects opening 57. Afirst waste portion 70 has a first metal detector 71 and an indicatorsystem with a visual alarm indicator 65 for providing a notificationwhen a metal item passes through the first opening 56. A second wasteportion 75 includes a second metal detector 76 and an indicator systemwith another visual alarm indicator 65 for providing a notification whena metal item passes through a second waste opening 57. An electronicsmodule 90 operates metal detector 71 and metal detector 76independently, and an audio alarm indicator operationally associatedwith the electronics module is activated whenever the electronics moduledetects the passage of a piece of metal into a waste portion. In the oneembodiment of the present invention in FIGS. 1-10 and 20-22, the twovisual alarm indicators 65 are situated along the bisection line forvisual indication. The top housing 50 is made up of a top coil housing52 secured to a bottom coil housing 54 leaving a hollow cavity 55 withinto house the transmitter coil(s) and receiver coil(s). A framework 105supports the coils in a defined arrangement within the hollow cavity.The bottom housing 54 is secured to the distal end 44 of the centerupright body 40.

Bag supports 61 are situated at the two furthest points along thebisection line 62 of each of the openings 56,57 of the top coil housing52 to aide in holding of inserted waste bag 64. The bag supports 61 makeuse of friction to help maintain a bag 64 in position after it has beensecured within an opening 56,57 of the waste cart 10. One embodimentincludes a plurality of bag supports 61 located along the upper surfaceof the top coil housing 52. The top housing 50 may also include aplurality of bag retainers 63 (FIGS. 3 and 4). The bag retainers 63function by a person pushing part of the bag 64 within the bag retainer63 and a spring action of the bag retainer helps to maintain the bag inposition. Ensconced within the top housing 50 is a set of three coiledlengths of electrical wire. One of the coils, the transmitter 100,encircles the full perimeter of the top housing 50. Each of theremaining two coils, i.e., the receivers 110, are disposed singularlyaround the perimeter of each of a respective one of the openings 56,57.The center upright body 40 provides structural support for the tophousing 50 and provides a means for containing the electricalconnections extending between the top housing 50 and the base housing20.

As stated previously, the electronics module 90 is contained within thebase housing 20. The electronics module 90 is connected (operationallyassociated) with the coils 100,110 and is connected to a plurality ofvisual alarm indicators 65 located on the top housing 50 and to an audioalarm indicator 67 (i.e. a speaker), which provides auditory indicationwhen a metallic object passes through an opening 56,57. In oneembodiment of the present invention, logic is provided to automaticallypower down the waste cart 10 after a defined period of time in order toconserve battery power. A means for powering the waste cart 10, whileconnected to structural power (i.e., a wall outlet) or while mobile, areprovided within the base housing 20. The waste cart 10 can be poweredeither by being plugged into structural wiring or via an internalbattery when not plugged in. The switch over from one power source toanother occurs without the intervention of the user and does not affectthe operation of the system. A plurality of caster wheels 35 areattached to the lower surface 24 of the base housing 20 to allow thewaste cart 10 to be easily moved. In one embodiment of the presentinvention, the cart is intended to be used as the primary location fordisposal of all objects not considered to be defined as sharps. Inanother embodiment, the cart is intended to be used as the primarylocation for disposal of all objects, including those defined as sharps.

The motion of a conductor (i.e., a metallic object or any materials thatwill conduct electricity) through a magnetic field results in minutecurrents being generated within the conductor. As the object passesthrough the electric field, there is an electrical current induced inthe object which can then be detected by the cart 10. The magnetic fieldcan be generated by a permanent magnet or by the application of the flowof electricity to a coil of conductors. As a conductor enters into themagnetic field, the field will induce currents of electrons that willswirl within the conductor much like the small swirling currents in aflowing body of water. These currents remain as the external fieldexists. If the field is removed, the currents within the conductor willremain temporarily. As there is no input of energy to support thecurrents, the currents will decay over a period of time. With conductorspossessing high conductivity, these currents will decay slower thanthose in a lower conductivity conductor. With the external fieldremoved, and before the currents have disappeared, the eddy currentswill themselves develop a magnetic field. In the opposite manner ofenergizing a coil to produce a magnetic field, if a coil of conductorsis placed within a magnetic field, a voltage will be generated along thelength of the coil. This theory is used to detect the presence of metalnear a conductor coil.

There are two primary methods for utilizing these components to detectmetal: continuous wave (CW) or pulse induction (Pl). In a CW system, acontinuous signal is generated by a coil transmitter which develops amagnetic field around the coil. A receiver coil 110 is able to pick upthe signal from the coil transmitter and the two signals are compared.If an object that can carry a magnetic field enters into proximity tothe coil transmitter 100, the signal between the coil transmitter 100and the receiver coil 110 is disrupted. This disruption is the basis forCW detection systems.

A system operating on a Pl will pulse an environment generating a cyclicmagnetic field (FIG. 23). When the transmitter coil 100 is turned off,any conductor that was within the transmitter coil's magnetic field willgenerate a magnetic field as it decays. A receiver coil 110 is able tothen detect the decaying magnetic field from the object and in thecontrol system is able to distinguish that an object was present. FIG.23 illustrates the pairs of magnetic fields 120. Looking now to FIG. 24,there is illustrated an embodiment of the perpendicular coil arrangement115.

Looking now to FIG. 25, there is illustrated a mid-level diagram of oneembodiment of the present invention. FIG. 25 includes an illustration ofthe electronics module 90 which is operationally associated with anacceleration motion detection module or accelerometer 83. Theelectronics module 90 is operationally associated with switch 80 and oneor more visual power indicators 81. The electronics module is alsooperationally associated with a visual motion detection camera 82 whichaids in deactivating the detection process while the cart 10 is inmotion. FIG. 25 also details an arrangement of the transmitter coil 100,a pair of detection coils 110, a pair of detection indicators 65, a pairof perpendicular coils 115, and an audio alarm indicator 67, all ofwhich are operationally associated with the electronics module 90. Alsoincluded in FIG. 25 are a main plug 85, a cord reel 86, a fuse 87, apower supply 88, and a battery 89.

The current waste cart 10 is an improvement on a previous version of ametal detecting waste bin. The previous version of the device consistedof a single opening with all circuitry and components contained withinthe top cap of the cart. The device operated on the CW system of metaldetection and could only reliably detect ferrous objects. The cartcontained a counter, an on/off switch, and a variety of other controls.The cart required a calibration period that was approximately 30seconds.

The waste cart 10 of the illustrated preferred embodiment of the presentinvention demonstrates the following improvements over the existing art:

-   -   The waste cart 10 now has the ability to detect both ferrous and        non-ferrous objects which include but are not limited to: iron,        steel, stainless steel, titanium, copper, aluminum, silver, and        gold.    -   The waste cart 10 is able to discern between high conductivity        objects such as aluminum and lower conductivity objects such as        steel.    -   The waste cart 10 has the ability to retain a significant        ability to detect objects while in close proximity to        environmental interferers. This is achieved by measuring the        response from the receiver coils and adjusting the threshold        gain accordingly, essentially increasing the ADC range in FIG.        19.    -   The waste cart 10 needs only a very short period of time from        completely off to be ready to detect (in the range of 0.1 to 10        seconds, 0.1 to 6 seconds, 0.1 to 4 seconds, 0.1 to 2 seconds,        or any combination thereof).    -   One embodiment of the waste cart 10 possesses two openings which        can be configured to detect on both sides or be set to detect on        a single side.    -   The design of the waste cart 10 facilitates the full use of the        volume of a waste bag 64 allowing it to bulge beyond the        perimeter of the base housing 20 and top housing 50 of the waste        cart 10.    -   The design of the waste cart 10 removes the need to lift a        potentially heavy waste bag vertically out of the bin, and        instead allows a bag to be removed, horizontally.    -   The waste cart 10 is turned on with a kick switch.    -   The only task a user must do to bring the waste cart 10 to full        operation is to kick the on/off foot switch.    -   The waste cart 10 possesses an RFID reader which is able to read        RFID tags as they pass through the openings 56,57.    -   The waste cart 10 possesses the ability to disable the alarm if        the cart is being moved within a room.    -   The waste cart 10 has the ability to be configured with multiple        sets of coils 100,110 which can be turned on to reduce the        detection window to help reduce external interferer influences.        For example, in the above-described embodiment of the present        invention, turning on additional coils refers to the optional        perpendicular coils 115. The perpendicular coils possess a        detection field which is perpendicular to the standard        horizontal orientation of the fields of coils 100,110. Using        some signal processing, the perpendicular detection field can be        used to validate a detection vs external interferers such as        rebar in the floor. The effect is much like a Venn diagram of        the sets of detection fields, which help to narrow the spatial        detection field.

One embodiment of the present invention discloses a waste disposalsystem 10 comprising a base housing 20; a center upright body 40 whichhas a proximal end 42 and a distal end 44, wherein the proximal end 42is secured to the base housing 20; a top housing 50 which is secured tothe distal end 44 of the center upright; wherein the base housing 20,center upright body 40, and the top housing 50 each is formed of amaterial that is amenable to disinfectant in the hospital environmentand has surfaces contoured for easy cleaning in the hospitalenvironment. The top housing 50 has at least two separate disposalportions: a first waste portion 70 for waste other than sharps, thefirst waste portion 70 having an opening 57 large enough to receivewaste that is typically other than sharps in the hospital environment;and a second waste portion 75 for waste other than sharps, the secondwaste portion 75 having an opening 56 large enough to receive waste thatis typically other than sharps in the hospital environment. A barrier 58separates the first waste portion 70 from the second waste portion 75,within which part of a metal detector is located and an indicator systemfor providing a notification when a metal item is unintentionally placedin an opening, wherein the metal detector includes a receiver coil 110and a transmitter coil 100 oriented perpendicular to the passage ofwaste to allow for more accurate detection in the passageways whilesimultaneously limiting the detection above and below the coils. Anelectronics module 90 operates each of two metal detectors independentlyof one another, and an audible alarm indicator is operationallyassociated with the electronics module 90, which is activated wheneverthe electronics module detects the passage of a piece of metal throughone or more of the waste openings 56,57.

In one embodiment, the above waste disposal system may be configuredwherein the coils are set up to be excited electromagnetically bywaveforms in configurations such as continuous-wave (CW) or a pulseinduction (Pl). In another embodiment, the waste disposal systemutilizes a differential coil arrangement including, for example, aquadrupole arrangement, wherein a single transmitter coil 100 encirclesboth the first waste opening 56 and the second waste opening 57 and afirst receiver coil is set to detect metal and a second coil is set tocancel external effects. In still another embodiment, the above wastedisposal system further includes a blocking shield to help isolate oneregion magnetically from another. The blocking shield is comprised ofMu-metal.

Metal Detection

The control circuitry operates in a cyclical nature with a detectionperiod representing a transmitted pulse, sampling of values andaccessory processes. Each detection period lasts 10 milliseconds with arate of 100 Hz in one embodiment.

Looking to FIG. 11, there is illustrated one embodiment of a detectionalgorithm used in the present invention. The detection cycle starts atstep 140 with the energizing of the transmitter coil (as seen in FIG.12). Step 141 represents an increase in the startup counter whichprovides a startup interval to allow calibration to the environmentbefore detection is initiated. Step 142 represents the calibration andsetting the reference number and calibrating the digital-to-analogconverter (DAC) to center during the startup interval. Step 143represents the end of a transmitted pulse.

Step 144 (the “Take ADC Value” step) represents the acquisition of ananalog-to-digital converter (ADC) value. This value constitutes athreshold for detection. FIG. 11A further schematically illustratesthis, which includes: step 162, wherein the ADC value is obtained from areceiver coil; step 163, wherein the ADC value is assigned its currentvalue plus the DAC value; step 164, wherein a determination is madewhether the new ADC value is zero; step 165, wherein no detection ismade upon a positive determination in step 164; step 166, wherein adetection is made upon a negative determination in step 164; and step167, wherein the DAC is adjusted so that the ADC value equals zero.

Both hardware and software are employed to make a detection andeffectively drive the ADC value to zero upon detection. This causesnotification when an interferer causes a false alarm, but onlymomentarily as a DAC control signal brings the measured ADC value tozero by means of a summing node. One embodiment would allow the ADCvalue to be summed with a DAC control voltage by an operationalamplifier configured as a summing amplifier. The resulting output wouldbe supplied to the algorithm as the ADC value. The algorithm would thenseek to drive this measurement to zero while announcing a detection aslarge adjustments are made. These adjustments allow for largeinterferers to be nulled out with a temporary announcement whilesubsequently announcing detection of intended objects after the ADCvalue is driven to zero. This behavior is illustrated starting with step145, which determines whether the value is greater than the center valueset in step 142, taking into account a standard deviation. If the ADCvalue in step 145 is greater than the center reference the startupcounter is reset and the DAC value is determined (step 147). If the DACvalue equals zero, then we move on to step 148, which is to increase thecenter. This process will eventually null an interferer and allow fordetection of intended objects given that the control signal is not atits limits. Proceeding to step 149, where it is determined whether thereference is less than 250. If it is not then there is an inability todetect (step 150), and if it is then we return to step 144, with anacquisition of the ADC value. If the DAC value from step 147 does notequal zero, then we proceed to step 151, wherein there is a decrease ina control signal, namely the RX control voltage (or an equivalentregulation control via current mode instead of voltage mode), whichtakes us to step 152, wherein the ADC value is taken and we proceed tostep 145 again. If the ADC value is not greater than the center value atstep 145, taking into account standard deviation, then we proceed tostep 153 which determines whether the value is less than the centerminus the acceptable deviation. If the result of step 153 is negative,then we move on to step 160 which is no detection; of course it will beappreciated that at this point operation would cease until the end ofthe next pulse, whereupon the sequence of FIG. 11 starts again. If theresult of step 153 is positive then the startup counter is reset and wemove on to step 154, where it is determined whether the DAC value isequal to 255. If the answer is yes, then we move on to step 157, whichis to decrease the center. Proceeding to step 158, it is determinedwhether the reference is greater than 5. If it is not then there is aninability to detect (step 159) and if it is, then we return to step 144,with an acquisition of the ADC value. If the DAC value is not equal to255 in step 154, we proceed to step 155 which is to increase in acontrol signal, namely the PIC input voltage (or an equivalentregulation control via current mode instead of voltage mode). We thenproceed to step 156, wherein the ADC value is taken again, after whichwe return to step 153 to determine whether the ADC value is less thanthe center value minus the standard deviation. In one embodiment of thepresent invention, steps 147 through 160 are utilized as backgroundcompensation.

In FIG. 12, the solid black line represents the value read from the sumof the two detection coils 110; this is the ADC value. This read valueis a conversion of analog voltage level from the sum of the twodetection coils being processed through an analog-to-digital Converter(ADC). It further will be recalled from above that the DAC value isdependent upon the ADC value via hardware. The physics relating to theADC limit the range the ADC can read which shows as the flat line whenthe transmitter is operating. Once the transmitter is turned off, thereis a period where the ADC is shut off to let the electronics settle.After a period of time, the ADC is turned back on. The solid black lineillustrates the characteristic detected voltage curve read by the ADCwithout a detectable object within the detection field.

The two detection coils 110 are balanced and operate in unison todiscriminate the detection side. The coils are balanced to assist in thefine discrimination of changes of voltages. A metallic object passingthrough the field of the coil connected to the positive leg of thesumming junction would result in a positive deflection of the ADC value.Conversely, as a metallic object passes through the detection coilconnected to the negative leg of the summing junction, the result wouldbe a negative deflection in the ADC value. This behavior is shown inFIG. 13. The entire curve deflects as a metallic object passes througheither of the detection coils, but there is generally a proportionallygreater change in the ADC value closer to the shut off of thetransmitter than there is farther from the transmitter shutoff.

The system operates very quickly and processor time must be managedappropriately to ensure accurate readings. Rather than take ADC valuesalong the entire detection period, sampling values are established,shown in FIG. 14. The vertical lines S1, S2, and S3 represent a systemwith three sampling points. The vertical lines illustrate the period intime when an ADC value is taken. The circular dots in FIG. 14, arerepresentative of the ADC value being read. Of course, additional orfewer points can be read, and three is only exemplary. Indeed, manysumming points could be taken, with the summing points being weighted tomake a digital filter. DSP could be performed with these points usingadditional math, many points could be taken and compared to a look uptable for discrimination.

In an effort to reduce noise which is present in any system, theaverages of these points are taken over a period of sixteen samples.There is a trade off in performance when averaging the samples. A sampleoccurs during each detection cycle, therefore averaging sixteen samplesrequires sixteen cycles to transpire. If there is a detectable valuethat is read, that value must be present in the detection field longenough for its effect to pass through the averaging processing andregister a detection. If too many samples are used, the system couldmiss quickly traveling objects. If too few samples are taken, the effectof noise can lead to false positives. The system relies on sensitiveelectronics looking at very minute deviations in voltages which makenoise a significant factor in the performance balancing.

For discussion of detections, this description will be referring tosampling point “S1” in the figures but the sample statements hold trueto any of the detection points. The system acquires the averaged ADCvalues at each of the sample points. These averages become the restingvalue. If the average deviates from this value, the system recognizesthe behavior as a detection caused by a metallic object passing throughone of the coils. Noise is still a factor, even with averaging, which tocompensate a deviation window is established, seen in FIG. 15. The ADCvalue may vacillate within this window without causing a detection. If,however, the value is great enough, the system will recognize thissituation as a detection. This deviation can either be positive FIG. 16or negative FIG. 17 depending on which detection coil the metallicobject has passed through.

The detection circuitry reads any field generated by any metallicobject. This may be a metallic object passing through the detectioncoils 110 or it could be an object next to the device, defined as aninterferer. Under ideal operating conditions, the system is set so thesignals within the detection coils 110 are far greater than that of thesurrounding objects. Significantly large interferers or quantities ofinterferers in close proximity to the detection coils can appear as ifthey were an object passing through the detection coils and signal afalse positive. To address this issue, the system takes advantage of thedifference in time base between a proper signal and interference fromthe environment. An object passing through the openings as if it werebeing thrown away will have a relatively quick transient change whencompared to the signal change of the entire waste cart 10 being movedaround a room. If the cart is moved in close proximity to a largeinterferer, the control system will recognize a change in ADC value andsignal a detection. As the ADC value remains the same, the system willrecognize this value as most likely an interferer and adjust itsthreshold value to establish a new reference value with a proper windowas shown in FIG. 18. In FIG. 18 the solid grey line represents theprevious characteristic ADC response. The dashed grey line representsthe characteristic signal when the cart is placed next to an interferer.The detection window is adjusted by the system to compensate for thechange in environmental response.

Of course it will be appreciated that the foregoing steps null outthings that a receiver coil picks up over long periods of time(relatively speaking). The foregoing characterization thus is to someextent a generalization or characterization; the system does notformally recognize a value as most likely being an interferer, butinstead simply compensates as the interference remains present over timeby moving the reference window up or down within the total physicallyachievable range; there is constant adjustment to the environment. If alarge piece of metal is detected, the system compensates, and moves itsdefinition of a detection within the total detection range. A change,any change, will result in detection and the alarm sounding. If thatchange is a fast moving piece of metal trash, a detection is properlymade and notification given or alarm sounded. If the cart is beingmoved, then avoidance of false detections and false alarms is providedby deference to the motion detection system used (accelerometer and/orcamera, for instance) that disables the alarm, notification, and/orperformance of the detection itself. In code, the system never itselfidentifies whether a large interference exists. There thus is anadvantage afforded by a time difference, but no formal determination ismade regarding duration of interference nor any logic incorporated forreacting to such a formal determination.

In will also be appreciated that there are instances where an interferermay be too close or too powerful of a response that the signal reachesthe limits of the ADC and the signal becomes clipped FIG. 19. Thisclipping is unavoidable since the ADC can only operate within physicallimits of the chip. In the case illustrated in FIG. 19, any furtherdeflection of the curve will not be seen by S1 or S2 since they arewithin the clipped region. The signal at S3 however, still retains someof its ability to detect changes and can therefore still detect certainlarger objects passing through the coils. If the cart ends up in asituation where it is not able to perform properly it will let out acycling tone to let the user know it is not able to operate correctly,150 and 159.

Perpendicular Coils

The current coil arrangement places the coils in a plane parallel to theground. In this orientation, the detection circuitry and coils are moresensitive to metallic objects both above (towards the ceiling) and below(towards the floor) the coils. To help reduce the influence ofinterferers, a second set of coils, disposed perpendicular to the coilsparallel to the ground (FIGS. 23 and 24) can be activated. The overlapbetween the two operational sets of coils acts to define the region ofmost sensitive detection. The theory was tested via setting a commercialcoil based metal detector product in this arrangement. The detector wasnot sensitive to metallic objects in the floor or ceiling but possesseda higher sensitivity to metallic objects about the circumference of themain detector coils. In one embodiment of the present invention, bothsets of coils operate in alternate turns of detection. A logic schemewas constructed that coordinates the detection of both sets of coils,effectively narrowing the detection space to an optimal size.

Cart Movement Sensing

A metal detector relies on the disturbances of electrical fields todetermine if a metallic object is present or not within its field ofdetection. This operation makes it nearly impossible to distinguishbetween a metallic object being moved into the field or if the field isbeing moved into close proximity of the detector. This situation ispertinent to the current device in that if the device is moved intoclose proximity to a metallic object, say a table or cabinet, thedetector will register this object as a detected object and signaldetection. This detection is undesirable in that the waste cart 10 isintended to detect objects passing into the field surrounding eachopening 56,57 at the top of the cart. A detection resulting from thewaste cart being moved into close proximity of a metallic object wouldbe viewed as a false detection and appear as an error in the cart. Toaddress this issue, methods have been implemented to disable thedetection function while the cart is in motion.

One of the methods for disabling the alarm while the cart is in motionis by means of an accelerometer 83. The accelerometer causes disablementof the detection and/or notification while the cart is being moved fromone location to another. It has been assumed that while the cart isbeing moved, there is a small likelihood of a user passing an article ofwaste through the detection field. Assuming this is the case, since thesensor will disable the detection and/or notification while in motion,it will not be apparent to the user if they move the cart into closeproximity to a metallic object thus causing the circuitry to register adetection as it was a false detection to begin with.

Another method for detecting motion of the cart is with a downwardfacing optical detector or motion camera 82. This detector registers thesurface of the floor. If the cart is moved, the detector will disablethe detection and/or notification until the cart has stopped moving andthe detector recalibrates to the new environment. The detectionpreferably would be disabled while the cart is in motion and would alsobe disabled during the calibration once it has stopped.

Either method is able to disable the detection and/or notification whilethe cart is in motion. However this is accomplished, it has beenidentified that it may be advantageous to signal the user that the cartis in motion and any articles passing through the cart will not bedetected and/or noticed. This signaling of the user can be visual orauditory.

Cart Cross Talk

In one embodiment of the present invention, two waste carts 10 exist ina relatively close proximity to one another. When this occurs, each carthas the ability to create a false detection on the other cart. Methodsfor dealing with this cross talk have been explored. As describedearlier, each cart accomplishes metal detection by creating a magneticfield by applying an electrical current through a wire loop for a shortamount of time. Once, the current is shut off, the cart records themagnetic fields of any metallic objects within proximity to the cart.This scheme happens in a cyclic fashion at a set frequency. If two cartsare placed in close proximity of each other, the likelihood of thedetection cycles overlapping is small as the detection cycle is a smallpercentage of the frequency period. As systems are not perfect, thefrequency on one cart will be slightly off from the other cart. Thiswill cause the detection point in one cart to drift in relation to theother cart. If one cart happens to be recording the magnetic field ofthe surroundings looking for metallic objects when the other cart iscreating a magnetic field, a detection will be recorded on the firstcart. It is thus imperative that the detection period for each cart iskept away from the detection period of the other cart.

The most basic method at achieving interval spacing has been utilizingthe 60 Hz AC wall power signal to acts as a clock for all of thesystems. There are generally three phases of power that enter abuilding. Each of the phases is 120 degrees out of phase with the next.The carts could use the AC wall frequency to set when the signaling anddetecting phases occur and not interfere with other carts (shownschematically in FIG. 27).

A more complex method of detection spacing involves the carts being ableto communicate with other carts nearby. Through a wireless protocol, acart would be designated as a master cart 170 charged with setting thedetecting timing for any carts (slave carts, 175) within distance of themaster cart 170 (shown schematically in FIG. 26). With the detectiontiming set and actively monitored, there would be less chance of falsedetections due to cross talk.

Power Line Filtering

The installation wiring and associated electrical equipment result in arelatively noisy environment for the metal detectors to operate in. Tocombat this issue, the frequencies of the power lines have beenselectively filtered out. This allows for more consistent operationacross multiple environments.

Isolation of Detection and Power Circuitry

When powered from installation wiring, the unfiltered power causes noisein the detection system. To help compensate for this noise, thedetection circuitry and power handling circuitry is electricallyseparated. This results in higher achievable accuracy and less falsedetection.

RFID (Radio-Frequency Identification)

It was determined through operational studies that it would beadvantageous for the carts to be able to track items with attached RFIDtags. This would allow for the carts to detect and track items which maynot be metallic. To accomplish this, the carts are fitted with an RFIDantenna and detection circuitry 125 (FIG. 28). As an RFID tagged itempasses through the opening, the RFID circuitry energizes the tag. Thetag broadcasts the information on the tag. The RFID circuitry 125detects the broadcasted information and is able to register that theitem has passed through the opening and into the waste bag.

The invention described herein also includes any method of using thewaste cart/medical waste disposal system to detect metallic objectsand/or prevent the loss of equipment and supplies.

Any method described herein may incorporate any design element containedwithin this application and any other document/application incorporatedby reference herein.

In one embodiment of the present invention, the waste cart 10 isintended to be used in the operating room after a surgery has beenconducted and the patient has been removed from the room. It has beendetermined that valuable equipment is being accidentally and/orinadvertently thrown away during the clean up after a medical procedure.This loss is accidental wherein equipment becomes lost with the medicaldrapery used in a medical procedure and is not found by the time thedrapes have been thrown away. The waste cart 10 has been designed tohelp mitigate the loss from this modality.

In another embodiment of the present invention, the waste cart 10 isintended to be used within any environment where valuable items arethrown away which have a metallic component capable of being detected bya waste cart as described herein. Those environments include, but arenot limited to, machine shops, automobile garages, assembly plants,laboratories, manufacturing plants, and similar facilities.

In one embodiment, the waste cart 10 is fit with two waste bags 64 aboutthe two openings 56,57 on the cart. A bag 64 is passed over the two bagsupports 61 at the corners of one of the half circle openings 56,57. Thebag 64 is pulled taught, twisted near one of the outer perimeter bagretainers 63 and pressed into the bag retainer. The waste cart 10 willbe used as a standard waste receptacle prior to and during a procedure.At the conclusion of a procedure, the patient is removed from the roomand the cleanup commences. Once the patient has been removed the wastecart 10 is positioned for ease of use. The cart is then turned on viathe power switch 80 (i.e., kick switch). A visual indicator (notillustrated) on the sides of the cart will illuminate when on to signalto the user that the cart is ready to receive waste. The cart is thenready to detect metallic objects passing through it. To the user thisappears instantaneous, not requiring a long calibration period prior touse. Waste is placed into the openings 56,57 of the cart as it would bea normal waste receptacle. If a metallic object passes through theopening 56,57 then an audible tone will be played through the speaker 67and the visual indicators 65 on the top housing 50 of the cart willlight up. After all waste has been disposed of or when a bag 64 has beenfilled, the technician removes the bag from the bag retainer 63 on theside of the top housing 50 and pulls the full bag from the side of thecart. A fresh bag can be replaced if desired or necessary. The wastecart 10 is wiped down to clean any foreign matter from its surface andturned off. If the waste cart 10 is not turned off, it willautomatically turn off if left without a detection for 15 minutes. Aretractable power cord can be extended to reach the nearest powerreceptacle for charging of the internal battery.

In another embodiment, the present invention includes a method fordetecting metallic objects as they pass through a waste cart 10including the steps of:

-   -   (a) providing the waste cart 10 comprising a base housing 20, a        center upright body 40 which has a proximal end 42 and a distal        end 44, the proximal end 42 being secured to the base housing        20, a top housing 50 secured to the distal end 44 of the center        upright 40, wherein the top housing 50 has two or more disposal        openings 56,57 for two or more separate disposal portions        comprising, a first waste portion 70 for waste other than sharps        which has a first metal detector 71 and an indicator system for        providing a notification when a metal item passes through the        opening 57, and a second waste portion 75 which optionally        includes a second metal detector 76 and an indicator system for        providing a notification when a metal item passes through the        other opening 56, an electronics module 90 which operates each        metal detector independently of one another and an alarm        indicator 65,67 operationally associated with the electronics        module 90 which is activated whenever the electronics module 90        detects the passage of a piece of metal through one or more of        the waste openings 56,57;    -   (b) activating the electronics module 90 and metal detectors        71,76;    -   (c) collecting waste generated during a procedure by placing the        waste through the disposal openings into either the first or        second waste portions 70,75;    -   (d) activating the alarm indicator in the event that one of the        metal detectors indicates the passage of a metallic object        though a detection field;    -   (e) retrieving the metallic object from the first or second        waste portions 70,75; and    -   (f) repeating steps (b) through (e) until the desired waste is        collected.

In one embodiment, the waste disposal system used in the above methodmay be configured wherein the coils are set up in either a constant wave(CW) configuration or a pulse induction (Pl) configuration. In anotherembodiment, the waste disposal system used in the above method utilizesa quadrupole arrangement, wherein a single transmit coil 100 encirclesboth the first waste opening 56 and the second waste opening 57 and afirst receive coil is set to detect metal and a second coil is set tocancel external effects. In still another embodiment, the above wastedisposal system used in the above method further includes a blockingshield to help isolate one region magnetically from another. Theblocking shield is comprised of Mu-metal.

Regarding step (c) of the method described herein, a “procedure”encompasses a variety to tasks including a medical or surgicalprocedure, the manufacture of a device or component, the assembly of adevice or component, the repair of a device or component, or any otheractivity within any environment where valuable items have a metalliccomponent capable of being detected by a waste cart as described herein.

In describing the invention, it will be understood that a number oftechniques and steps are disclosed. Each of these has individual benefitand each can also be used in conjunction with one or more, or in somecases all, of the other disclosed techniques. Accordingly, for the sakeof clarity, this description will refrain from repeating every possiblecombination of the individual steps in an unnecessary fashion.Nevertheless, the specification and claims should be read with theunderstanding that such combinations are entirely within the scope ofthe invention and the claims.

Additional aspects and features of the invention are disclosed andrevealed by the flowcharts of FIGS. 29-37 which schematically illustratesteps and routines performed by processor-executable code for performingone or more methods of detection in waste receptacles in accordance withpreferred embodiments of the present invention. Such code may becontained in non-transitory machine-readable medium of the electronicsmodule of the base housing in cart 10, for example.

The present invention may be embodied in other forms without departingfrom the spirit and the essential attributes thereof, and, accordingly,reference should be made to the appended claims, rather than to theforegoing specification, as indicating the scope of the invention.

What is claimed is:
 1. A waste cart, comprising: (a) a top housing inwhich a disposal opening extends; (b) a base housing comprising aplurality of wheels for moving the waste cart across a floor of a room;(c) a support extending between the base housing and the top housing andsupporting the top housing above the base housing at a heightaccommodating retention of a waste bag such that waste passing throughthe disposal opening is received within the waste bag; (d) a coilarrangement contained within the top housing and including (i) atransmitter coil comprising a wire loop that extends around andencircles a perimeter of the top housing, and (ii) two receiver coilseach comprising wire loops, only one of which receiver coils extendsaround and encircles a perimeter of the disposal opening; (e) anelectronics module connected to and operationally associated with thecoil arrangement and configured to detect passage of a metal itemthrough the disposal opening; and (f) an indicator system connected tothe electronics module, by which an indication is provided of adetection of passage of a metal item through the disposal opening; (g)wherein pulse induction is used to detect passage of a metal itemthrough the disposal opening, the electronics module and coilarrangement detecting passage of a metal item through the disposalopening during detection periods, each detection period following arespective pulse.
 2. The waste cart of claim 1, wherein the electronicsmodule is configured to perform steps, during each detection period, inwhich a calibration is done, in which an analog-to-digital convertervalue is taken, and in which one or more background interferers arecompensated for.
 3. The waste cart of claim 2, wherein the electronicsmodule is configured to perform steps, during each detection period, inwhich the analog-to-digital converter value is taken a predeterminednumber of times, the analog-to-digital converter value representing asumming of the two receiver coils using an analog-to-digital converter.4. The waste cart of claim 3, wherein the two receiver coils arebalanced and are configured to operate in unison for discriminating adetection side.
 5. The waste cart of claim 1, wherein the electronicsmodule is located within the base housing.
 6. The waste cart of claim 5,wherein the support contains electrical connections extending betweenthe base housing and the top housing for connecting the electronicsmodule and coil arrangement.
 7. A waste cart, comprising: (a) an uppersection comprising a top housing in which first and second disposalopenings extend, the upper section being configured to retain first andsecond bags for receiving waste therein that passes through the firstand second disposal openings, waste passing through the first disposalopening being received within a first bag and waste passing through thesecond disposal opening being received within a second bag; (b) a lowersection comprising a plurality of wheels for moving the waste cartacross a floor of a room; (c) a middle section extending from the lowersection and structurally supporting the upper section above the lowersection at a height accommodating bag retention from the upper sectionfor filling with waste; (d) a coil arrangement contained within the tophousing and including (i) a transmitter coil comprising a wire loop thatextends around and encircles a perimeter of the top housing, and (ii) apair of receiver coils each comprising wire loops, a first one of whichreceiver coils extends around and encircles a perimeter of the firstdisposal opening and a second one of which receiver coils extends aroundand encircles a perimeter of the second disposal opening; (e) anelectronics module connected to and operationally associated with thecoil arrangement and configured to detect passage of a metal itemthrough the disposal opening; and (f) an indicator system connected tothe electronics module, by which an indication is provided of adetection of such passage; (g) wherein pulse induction is used to detectsuch passage, the electronics module and coil arrangement detecting suchpassage during detection periods, each detection period following arespective pulse.
 8. The waste cart of claim 7, wherein the electronicsmodule is configured to perform steps, during each detection period, inwhich a calibration is done, in which an analog-to-digital convertervalue is taken, and in which one or more background interferers arecompensated for.
 9. The waste cart of claim 8, wherein the electronicsmodule is configured to perform steps, during each detection period, inwhich the analog-to-digital converter value is taken a predeterminednumber of times, the analog-to-digital converter value representing asumming of the two receiver coils using an analog-to-digital converter.10. The waste cart of claim 9, wherein the two receiver coils arebalanced and are configured to operate in unison for discriminating adetection side.
 11. The waste cart of claim 10, wherein the electronicsmodule and coil arrangement are configured such that a metal itempassing through the first disposal opening results in a positive changein the analog-to-digital converter value that is taken, and a metallicobject passing through the second disposal opening results in a negativechange in the analog-to-digital converter value that is taken.
 12. Thewaste cart of claim 7, wherein pulse induction is used in theelectronics module and coil arrangement to detect passage of a metalitem through either of the disposal openings.
 13. The waste cart ofclaim 7, wherein the pair of receiver coils of the coil arrangement arearranged generally horizontally, and wherein the coil arrangementfurther comprises a second pair of receiver coils arranged generallyvertically and located between the first and second disposal openings.14. The waste cart of claim 7, wherein the middle section is configuredto be secured to the top section, and wherein the top section isconfigured to be secured to the middle section.
 15. The waste cart ofclaim 7, wherein the indicator system comprises a visual alarmindicator, a speaker, or both.
 16. The waste cart of claim 7, whereinthe lower section further comprises a kick switch for turning on and offby foot detection of a metal item that passes through either of thedisposal openings by the electronics module and coil arrangement. 17.The waste cart of claim 7, further comprising a battery for poweringdetection of a metal item that passes through either of the disposalopenings by the electronics module and coil arrangement.
 18. The wastecart of claim 7, further comprising means for powering the waste cart.19. The waste cart of claim 7, further comprising means for disablingthe indication of a detection of passage of a metal item through eitherof the disposal openings while the cart is being moved.
 20. A wastecart, comprising: (a) a top housing in which first and second disposalopenings extend; (b) a base housing comprising a plurality of wheels formoving the waste cart across a floor of a room; (c) a support extendingbetween the base housing and the top housing and supporting the tophousing above the base housing at a height accommodating retention oftwo waste bags such that waste passing through a said disposal openingis received within a respective one of the two waste bags; (d) a coilarrangement contained within the top housing and including (i) atransmitter coil comprising a wire loop that extends around andencircles a perimeter of the top housing, and (ii) two receiver coilseach comprising wire loops, one of which receiver coils extends aroundand encircles a perimeter of said first disposal opening; (e) anelectronics module connected to and operationally associated with thecoil arrangement and configured to detect passage of a metal itemthrough the first disposal opening; and (f) an indicator systemconnected to the electronics module, by which an indication is providedof such a detection of passage of a metal item; (g) wherein pulseinduction is used to detect passage of a metal item through said firstdisposal opening, the electronics module and coil arrangement detectingpassage of a metal item through said first disposal opening duringdetection periods, each detection period following a respective pulse;and (h) wherein the electronics module is configured to perform steps,during each detection period, in which a calibration is done, in whichan analog-to-digital converter value is taken, and in which one or morebackground interferers are compensated for.